1. Field of the Invention
This invention relates generally to a materials lifting apparatus, and more particularly, but not by way of limitation, to an improved materials lifting apparatus for transporting pipe between a pipe rack and a derrick floor.
2. Description of the Prior Art
In the drilling of a well tubular goods, such as drill pipe, production tubing, casing, and the like, must be transported between a pipe rack or ground level and a derrick floor. The transporting of such tubular goods during the drilling operation is one of the most dangerous aspects of a well boring operation in the drilling of a well. For example, the various sections of pipe are generally laid down in horizontal rows on a pipe rack in a side-by-side relationship at a location in the vicinity of the drilling derrick, and the pipe must be transferred to and from the derrick floor, as necessary. Similarly, when pulling tubular goods from the bore hole of the well the joints of the tubular goods must be broken down from the string of pipe and returned to the pipe rack. Because of the weight of each of the various sections of the tubular goods employed in the drilling operation, and the necessity of moving such goods between the ground and the derrick floor, devices have heretofore been proposed to assist in the movement of the tubular goods in an effort to reduce the dangers encountered by those working on the well, especially where the danger is a result of the movement of the tubular goods between the ground level and the derrick floor.
Typical of the prior art devices are the pipe handling apparatus disclosed in U.S. Pat. Nos. 3,825,129 and 4,099,630. The pipe handling apparatus of the before mentioned patents employ a cable assembly which overhangs the derrick floor and the pipe rack, the cable assembly being adapted to move the pipe therebetween.
Various other pipe handling apparatus for transfer of pipe from a drilling rig floor to a pipe rack have heretofore been known. Many of the prior art devices have required men to physically move the pipe from the pipe rack to the lifting apparatus and vice versa, or have employed a plurality of cables, winches and the like which are unstable and often cause problems when such devices are employed to move pipe between the drilling rig floor and the pipe rack. Thus, the need has long been recognized for an improved lifting apparatus which can more efficiently handle tubular goods employed in the drilling of a well, as well as moving the tubular goods between a pipe rack and the derrick floor.